From: Marc Zyngier <maz@kernel.org>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/4] KVM: arm64: pmu: Set the CHAINED attribute before creating the in-kernel event
Date: Sun, 20 Oct 2019 11:11:28 +0100 [thread overview]
Message-ID: <20191020101129.2612-4-maz@kernel.org> (raw)
In-Reply-To: <20191020101129.2612-1-maz@kernel.org>
The current convention for KVM to request a chained event from the
host PMU is to set bit[0] in attr.config1 (PERF_ATTR_CFG1_KVM_PMU_CHAINED).
But as it turns out, this bit gets set *after* we create the kernel
event that backs our virtual counter, meaning that we never get
a 64bit counter.
Moving the setting to an earlier point solves the problem.
Fixes: 80f393a23be6 ("KVM: arm/arm64: Support chained PMU counters")
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
virt/kvm/arm/pmu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index c30c3a74fc7f..f291d4ac3519 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -569,12 +569,12 @@ static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx)
* high counter.
*/
attr.sample_period = (-counter) & GENMASK(63, 0);
+ if (kvm_pmu_counter_is_enabled(vcpu, pmc->idx + 1))
+ attr.config1 |= PERF_ATTR_CFG1_KVM_PMU_CHAINED;
+
event = perf_event_create_kernel_counter(&attr, -1, current,
kvm_pmu_perf_overflow,
pmc + 1);
-
- if (kvm_pmu_counter_is_enabled(vcpu, pmc->idx + 1))
- attr.config1 |= PERF_ATTR_CFG1_KVM_PMU_CHAINED;
} else {
/* The initial sample period (overflow count) of an event. */
if (kvm_pmu_idx_is_64bit(vcpu, pmc->idx))
--
2.20.1
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next prev parent reply other threads:[~2019-10-20 10:11 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-20 10:11 [GIT PULL] KVM/arm fixes for 5.4-rc5 Marc Zyngier
2019-10-20 10:11 ` [PATCH 1/4] KVM: arm64: pmu: Fix cycle counter truncation Marc Zyngier
2019-10-20 10:11 ` [PATCH 2/4] arm64: KVM: Handle PMCR_EL0.LC as RES1 on pure AArch64 systems Marc Zyngier
2019-10-20 10:11 ` Marc Zyngier [this message]
2019-10-20 10:11 ` [PATCH 4/4] KVM: arm64: pmu: Reset sample period on overflow handling Marc Zyngier
2019-10-22 11:34 ` [GIT PULL] KVM/arm fixes for 5.4-rc5 Paolo Bonzini
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